1. What is DNA Copy Number?

The DNA copy number represents the number of copies of a specific DNA molecule per unit volume. It's calculated from the DNA concentration and length, using Avogadro's number and the average molecular weight of a DNA base pair.

2. How Does the Calculator Work?

The calculator uses the DNA copy number equation:

Where:

• \( CN \) — Copy number (copies/μL)
• \( C \) — DNA concentration (ng/μL)
• \( L \) — DNA length (base pairs)
• 660 — Average molecular weight of one base pair (g/mol)
• 6.022 × 10²³ — Avogadro's number
• 2 — Accounts for dsDNA (two strands per molecule)

Explanation: The equation converts mass concentration to molar concentration, then calculates the number of molecules using Avogadro's number.

3. Importance of Copy Number Calculation

Details: Knowing the exact copy number is crucial for molecular biology applications like PCR, qPCR, sequencing library preparation, and genetic engineering.

4. Using the Calculator

Tips: Enter DNA concentration in ng/μL and length in base pairs. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why is 660 g/mol used?
A: This is the average molecular weight of one DNA base pair (dNTP), accounting for different nucleotide compositions.

Q2: Does this work for ssDNA?
A: For single-stranded DNA, remove the factor of 2 from the denominator.

Q3: What are typical copy number ranges?
A: For qPCR standards, common ranges are 10⁶-10¹⁰ copies/μL. For sequencing libraries, 10⁸-10¹¹ copies/μL.

Q4: How accurate is this calculation?
A: It provides a theoretical estimate. Actual values may vary slightly due to measurement errors and DNA purity.

Q5: Can I use this for RNA?
A: For RNA, use 340 g/mol as the average molecular weight per nucleotide instead of 660.